1. Field
The present invention is related to automatic cable stops and, more particularly, to such stops as employed in tow winches.
2. Prior Art
A number of cable stop mechanisms are available as evidenced by U.S. Pat. Nos. 2,426,051, 3,904,843, 3,052,878, 4,273,973, 2,927,170, 3,056,586 and 2,681,954. All of these patents in some manner stop a cable automatically. However, none are specifically designed for use in tow truck winches. Normally, in the operation of a tow truck winch, the engine is used to drive the winch and the cable is reeled in over a pulley located at the end of the winch boom. The end of the cable usually contains a hook, such as hook 113 shown in FIG. 1. The end of the boom 101 is usually formed of two plates, such as plate 115 and 201, shown in FIG. 2. Securing means, such as 112 shown in FIGS. 1 and 2, the hook 113 and the tow bar are usually too large to pass between the plates 115 and 201 or cannot pass between the pulley 202 and a top cover of the boom (not shown). Continued reeling, once the hook and securing means have reached the end of the boom can cause serious damage to the boom, pulley and surrounding personnel in the event the cable snaps. A simple, low cost safety device is a current need for such winches.
Most of the prior art patents listed above describe cable stop mechanisms for special applications, but none is designed for the particular application of the tow truck winch. A number of the prior art cable stop devices include complicated mechanisms, and special housings which increase cost and, in some cases, reduce reliability. Finally, all of the prior art devices use lever mechanisms or other linkages to actuate the switch, further increasing complexity and cost while reducing reliability.